Basic aluminum chlorides have several important industrial applications. Aluminum chlorides are used in the cosmetics industry as an active ingredient in for example, anti-perspiration preparations, or in hemostatic preparations. Aluminum chlorides are also used for hydrophobizing textile materials, as tanning agents and as flocculants for water treatment. Recently, aluminum chlorides have been used in the preparation of refractory substances and inorganic fibers.
Aluminum chloride has conventionally been prepared from chemical processes, such as the double conversion of other basic aluminum salts, by partial hydrolysis of anhydrous aluminum chloride, by thermal split-off of hydrogen chloride from aluminum chloride-hexahydrate or by reaction of aluminum hydroxides.
Aluminum chlorides have also been prepared by electrochemical processes. In German patent 27 13 236 (corresponding to U.S. Pat. No. 4,203,812, the disclosure of which is hereby incorporated by reference), electrolysis of aluminum chloride solutions at 50.degree. to 120.degree. C. with the liberation of chlorine for the preparation of polyaluminum chloride solutions is described. Futhermore, electrolysis of PAC solutions between two aluminum electrodes for increasing the molar ratio of aluminum to chlorine is described in German patent 23 09 610 (corresponding to U.S. Pat. No. 3,953,584, the disclosure of which is hereby incorporated by reference).
Both of these electrochemical processes require the use of a specially prepared electrolysis cell. Because these methods involve the liberation of chlorine, special precautions must be taken regarding protection of the environment and assuring the safety of the workplace.
The prior art methods also involve high energy costs. In addition, chlorine, a valuable chemical, is lost in these methods. If the liberated chlorine is to be captured, expensive recycling equipment has to be installed.